The eight-time Olympic champion and 11-times world champion Usain Bolt is among nine elite athletes who have partnered with fitness company Peloton for its newly released Champions Collection.

Peloton Interactive, Inc. is an exercise equipment and media company that allows monthly subscribers to remotely participate in classes via streaming media.

Inside Hook reported on Wednesday that Peloton announced the Champions Collection for which it was partnering with the likes of Bolt, tennis star Angelique Kerber, surfer John John Florence, Allyson Felix and Andre De Grasse, Paralympic long jumper Scout Bassett, Olympic gymnasts Becky and Ellie Downie, and former world-record-holding swimmer Kathleen Baker.

According to the online publication, athletes will likely not become formal instructors but will probably have pages built out on the platform, where subscribers can follow along with their favourite workouts or playlists.

World number one Ash Barty moved through to the last 16 of the Miami Open, where Simona Halep's campaign came to a premature end.

Defending champion and top seed Barty was too good for Jelena Ostapenko in Saturday's showdown between the former French Open winners.

Two-time grand slam winner Victoria Azarenka also moved through to the fourth round of the WTA Premier tournament.

Halep, however, succumbed to a shoulder injury in Miami.

CLASH OF PAST AND PRESENT NUMBER ONES

Barty and former world number one Azarenka will go head-to-head for a place in the quarter-finals.

Australian star Barty accounted for Ostapenko 6-3 6-2 as she extended her winning streak at the Miami Open to eight matches.

Barty, who tallied nine winners to 14 unforced errors, rallied from 2-0 down in the second set by reeling off six successive games to advance.

"Today felt like I was a lot sharper and switched on and ready to go from the very first point," Barty said afterwards.

Three-time Miami champion Azarenka trumped Angelique Kerber 7-5 6-2 in the third round.

Azarenka – the 14th seed – fought back from a 4-1 deficit in the opening set to get the better of the three-time major winner.

"She's a very talented player. I always have been a huge fan of her game and the way she plays, the way she handles herself. She has a lot of variety," Azarenka said on facing Barty. "She has pretty much every single shot there is. [It's] going to be a great match."

INJURED HALEP PULLS OUT

Two-time grand slam champion Halep withdrew due to a shoulder injury as Anastasija Sevastova benefited from a walkover.

"I'm very sorry to I have to pull out of the singles and doubles at the Miami Open, but my injury doesn't let me play here as expected," said Halep.

"I'm sad that I can't continue, I wanted to come here to give my best and play many matches but unfortunately I can't. 

"Hopefully next year I will come back healthy and better."

Next up for Sevastova is wildcard Ana Konjuh, who stunned 15th seed and reigning French Open champion Iga Swiatek 6-4 2-6 6-2.

SVITOLINA AND SABALENKA ROLL ON

Ukrainian fifth seed Elina Svitolina booked her spot in the round of 16 after overcoming fellow seed Ekaterina Alexandrova 7-6 (7-1) 6-4.

Two-time Wimbledon winner Petra Kvitova stands in the way of a quarter-final berth – the ninth seed was too good for 17th seed Johanna Konta 6-1 6-2.

Seventh seed Aryna Sabalenka, meanwhile, prevailed 7-6 (7-4) 6-4 against Veronika Kudermetova.

Belinda Bencic – the 11th seed – was sent packing 4-6 6-4 6-4 by Marketa Vondrousova, who will take on Sabalenka.

Ash Barty completed a great escape to stay alive at the Miami Open, where Simona Halep also progressed.

Barty faced a match point but the defending champion and world number one dug deep to prevail in three sets against Kristina Kucova on Thursday.

Romanian third seed Halep also needed three sets at the WTA Premier tournament in Miami.

BARTY PRODUCES COMEBACK

In her first match outside of Australia in more than 12 months, Barty survived to top qualifier Kucova in Miami.

Barty trailed 5-2 in the third set, with Kucova earning a match point at 5-3 but the Australian star saved it and won the final five games of the match to secure a spot in the round of 32.

Winner of the 2019 French Open, Barty sent down an equal career-high 15 aces in two-and-a-half hours.

"Today was really hard work, and I enjoyed every single minute of it," Barty said on court post-game. "There’s nothing like coming through a test like that, and now I get another opportunity in a couple days' time to play another tough match and test myself again."

Next up for Barty is 2017 Roland Garros champion Jelena Ostapenko, who outlasted Kirsten Flipkens 6-2 5-7 6-3.

HALEP REACHES MILESTONE

Halep brought up her 400th WTA main-draw triumph with a 3-6 6-4 6-0 victory over France's Caroline Garcia.

After dropping the opening set, Halep won 11 of the final 12 games to move through to the next round.

Halep won in one hour, 48 minutes, drastically improving on her first serve after the opening set while coming to grips with Garcia's kick serve.

"I needed time to get used to it and to get the rhythm," Halep said about Garcia's serve having improved her head-to-head record to 7-1, with Anastasija Sevastova awaiting in the last 32 after eliminating American sensation Coco Gauff.

Halep received attention on her shoulder early in the second. "I struggled with my serve," Halep said. "I struggled with my shoulder a little bit, so the attention was a little bit on the pain. [After that] I started to relax myself."

KERBER'S DOUBLE BAGEL

Three-time grand slam winner Angelique Kerber has been up and down in recently, but she flexed her muscles with a 6-0 6-0 humiliation of Renata Zarazua.

Aryna Sabalenka – the seventh seed – was another one to fend off match points before rallying 0-6 6-3 7-6 (11-9) past Bulgarian qualifier Tsvetana Pironkova in a gutsy.

Last year's French Open champion Iga Swiatek knocked off Barbora Krejcikova 6-4 6-2, while ninth seed and two-time Wimbledon champion Petra Kvitova got past Aliza Cornet 6-0 6-4.

Fifth seed Elina Svitolina survived to beat Shelby Rogers 3-6 7-5 6-3 and two-time major winner Victoria Azarenka benefited from a walkover.

Garbine Muguruza made clear she is "fighting for trophies" on the WTA Tour after knocking out defending champion Aryna Sabalenka at the Qatar Open. 

Muguruza prevailed in a high-quality contest that required a third set to decide the outcome, the world number 16 and two-time grand slam champion eventually triumphing 6-2 6-7 (7-5) 6-3 after two hours, 18 minutes on court. 

Sabalenka had won their only previous meeting but the third seed saw her hopes of retaining the trophy dashed, not helped by only managing to convert four of the 13 break-point opportunities she created in the match. 

Muguruza – who matched 41 winners with the same number of unforced errors – finished in fine style, claiming the final four games in a row to set up a meeting with Maria Sakkari, who defeated Madison Keys in straight sets. 

"I'm very motivated to play top players," Muguruza said in her post-match press conference, according to the WTA Tour's website. "Like everybody, I worked hard. I'm fighting for trophies, to play well in big tournaments, in good tournaments. 

"Today I was facing a top player, and I knew I have to go out there with a big, fighting spirit, and be strong to be able to win against these tough opponents." 

While the 2020 winner is no longer involved, former champions Victoria Azarenka and Petra Kvitova both made it beyond the second round with straight-sets wins in Wednesday's action. 

Azarenka, who claimed the title in 2012 and then returned to successfully retain it a year later, saw off qualifier Laura Siegemund 6-4 6-2. 

Kvitova, meanwhile, eased past Anastasia Pavlyuchenkova. The fourth seed went all the way in 2018 and is now into the last eight this year – a 6-1 6-3 result paving the way for a clash with Anett Kontaveit.

Top seed Elina Svitolina is also through – and will face Azarenka next – after needing little over an hour to defeat Misaki Doi 6-1 6-2.

Karolina Pliskova, the second seed, found life far tougher against Ons Jabeur however, eventually coming out on top 6-4 4-6 7-5 in a thriller.

Meanwhile, at the Lyon Open, second seed Fiona Ferro progressed to the last eight on home soil after opponent Tereza Martincova was forced to retire when 4-1 down in the second set, having already lost the opener too.

Alize Cornet is another French favourite hoping to make home advantage tell in the tournament; the fifth seed rallied from a set down to beat compatriot Clara Burel 1-6 6-1 6-3. 

Victoria Azarenka booked her spot in the second round of the Qatar Open with a 6-2 6-3 win over Svetlana Kuznetsova on Monday. 

It was the first time the pair had faced off since the final of the 2016 Miami Open and Azarenka, who won back-to-back titles in Doha in 2012 and 2013, struck first, eventually claiming the opening set in 44 minutes. 

She needed six match points to see off Kuznetsova in the second set to tee up a last-16 meeting with either Laura Siegemund or Elena Rybakina. 

There was also a win for former world number one Garbine Muguruza, who defeated Veronika Kudermetova 6-2 7-6 (7-4).

"Veronika was a very tough opponent," Muguruza told a media conference. "[I'm] just happy with this win. We played a year ago, and I remember it was a tough match. I'm happy to have closed it in two sets."

Fifth seed Kiki Bertens, meanwhile, was dumped out by a rampant Jelena Ostapenko in straight sets. 

The 2017 French Open champion hit 26 winners on her way to an emphatic 6-0 6-2 win against her Dutch opponent, who was playing her first match in five months following Achilles surgery. 

Anett Kontaveit overcame number seven seed beaten Australian Open finalist Jennifer Brady 6-1 6-2 to set up a second-round clash with Angelique Kerber, who beat Cagla Buyukakcay 6-4 6-2.

In the day's other match, Maria Sakkari beat Mayar Sherif 6-0 6-3. 

Meanwhile, teenage qualifier Clara Tauson shocked number one seed Ekaterina Alexandrova 6-3 6-4 in the first round of the Lyon Open. 

There were also wins for Arantxa Rus, Nina Stojanovic, Timea Babos, Greet Minnen and Fiona Ferro in France. 

Naomi Osaka said she was "really nervous" before facing Anastasia Pavlyuchenkova but showed no signs of that as she breezed into the second round of the Australian Open.

Osaka looked dominant on day one of the first grand slam of the year as she welcomed being able to play in front of a crowd at Melbourne Park, taking only 68 minutes to wrap up a 6-1 6-2 victory.

The US Open champion has beaten Pavlyuchenkova three times in a row after losing when they first met in 2017 but was wary of facing the Russian on Rod Laver Arena.

Third seed Osaka said: "I was really nervous coming into this match. I know that I've played her before, and it was really tough. I just wanted to play well.

"The most recent memory I have of playing her was in the Osaka final [that Osaka won 6-2 6-3 in 2019], so it's always really hard to play someone that good in the first round.

"For me, I feel like it might have also helped in a way because I calmed my nerves because I felt like I couldn't afford to be that nervous. But, yeah, it was a tough match."

Serena Williams and Simona Halep stormed into round two, but the 2016 champion Angelique Kerber crashed out with a 6-0 6-4 defeat to world number 63 Bernarda Pera.

Alison Riske and Wang Qiang were the only other seeds to fall, losing to teenager Anastasia Potapova and qualifier Sara Errani respectively, while Bianca Andreescu made a winning comeback.

Williams sisters among major winners to make serene progress

Serena Williams did not look at all troubled by a shoulder problem as she started her latest quest to win a record-equalling 24th major singles title with a 6-1 6-1 demolition of Laura Siegemund.

Her older sister, Venus, also advanced in straight sets, beating Kirsten Flipkens 7-5 6-2.

Iga Swiatek, the French Open champion, was too good for Arantxa Rus, winning 6-1 6-3, and Petra Kvitova got past Greet Minnen 6-3 6-4.

Kerber will not be claiming a fourth major crown this month after falling to Croatia-born American Pera.

Halep planning to oust another Australian

Two-time major winner Halep was a cut above Lizette Cabrera, winning 6-2 6-1 in 59 minutes, and is looking forward to facing another Australia in the second round in the form of Ajla Tomljanovic. 

"I like to be here, so I like to play Australians," Halep quipped.

"I feel good. My body is fit. It's always difficult to play a big hitter. So, I have to be strong on my legs, focus on myself and give my best.

"I expected a tough match because I played against her before and I know how it's gonna be. She's a good opponent, a good player, and I will focus just on myself like I do every time, but I'm ready for a good battle."

Andreescu back in business

Andreescu put her injury woes behind her, battling past Mihaela Buzarnescu 6-2 4-6 6-3 in her first match for 15 months.

The Canadian had not played in a grand slam since winning the US Open in 2019 but was back in business on John Cain Arena.

Eighth seed Andreescu said: "After the match, I sat down with my team a little bit, and I'm like, 'Oh, guys, here we go again, those three-setters' and they just started laughing because they obviously knew what they were getting themselves into.

"But those matches are super good for me in my opinion because it really shows that I can scramble when I really need to, or if there's some pressure I can dig my way through it somehow. When my back is against the wall, not only today, but I've noticed throughout my last couple tournaments in 2019, I've been able to pull through with those."

Garbine Muguruza continued her impressive form to book a meeting with Ash Barty in the Yarra Valley Classic final.

Muguruza, the Spanish sixth seed at the WTA 500 event, crushed Marketa Vondrousova 6-1 6-0 on Saturday.

The two-time grand slam champion has lost just 10 games in four matches on her way to the final.

Muguruza lost just eight points on serve against Vondrousova while converting five of 11 break points.

She will meet Barty in the final after the Australian benefited from Serena Williams' withdrawal as the 23-time grand slam winner deals with a shoulder injury.

Naomi Osaka and Victoria Azarenka also withdrew on Saturday from the Gippsland Trophy and Grampians Trophy respectively.

At the Grampians Trophy, Anett Kontaveit was given a passage into the semi-finals, where Maria Sakkari awaits after her 6-4 6-2 win over Angelique Kerber.

Jennifer Brady and Ann Li will meet in the other semi after wins over Barbora Krejcikova and Sorana Cirstea respectively.

Elise Mertens will play the Gippsland Trophy final after Osaka's withdrawal with the Belgian to face Kaia Kanepi, who overcame Ekaterina Alexandrova 6-3 7-6 (8-6) to reach her first WTA decider since 2013.

One in eight women in the Australian Open draw have already won a grand slam title.

One in eight. It is staggering that of the 128 players who set out in the hope of singles glory at Melbourne Park, there are 16 major champions among them, and perhaps never has it been so difficult to predict who will carry off the title.

Compare it to the men's draw, where there are just five grand slam singles winners, and where you would struggle to make a compelling case for any more than three of those this year, with apologies to Stan Wawrinka and Marin Cilic.

As long-running dynasties near their end on the men's and women's tours, the WTA is a lengthy step ahead of the ATP with a cast of appealing characters already assuming leading roles.

The leader of the pack

Three-time grand slam champion Naomi Osaka is at the forefront of a school of rising stars, but she has impressive rivals for company.

The last four years have seen the 15 women's majors won by 12 different players, whereas in the men's game, Rafael Nadal (6), Novak Djokovic (5), Roger Federer (3) and Dominic Thiem (1) have creamed off all the top prizes in the same period.

Often criticised in the past for a perceived lack of depth, in the years when Serena Williams won seemingly at will, the women's tour has exploded with a rush of bright and young talent.

Osaka is a revelation and a leader, on and off the court. Twice a US Open champion now, and a winner in Australia two years ago, the 23-year-old Japanese star took a powerful stance for racial equality at Flushing Meadows back in September, at the height of Black Lives Matter protests. She wants to achieve even more off the court than on it, where she looks assured of one day leaving an impressive legacy.

If there is any area where Osaka's game falls down it is consistency. She has surprisingly not passed the fourth round in 14 of her 17 grand slam appearances, but on every occasion she has gone beyond that stage it has been en route to lifting a trophy.

In hot pursuit

Last year's three slam champions were, at the times of their triumphs, just 21 (Sofia Kenin - Australian Open), 19 (Iga Swiatek - French Open) and 22 (Osaka - US Open).

The women's game has not seen anything comparable in terms of youthful winners of its blue riband tournaments since 2004, when the 21-year-old Justine Henin won in Australia, Anastasia Myskina landed the Roland Garros title at 22, Maria Sharapova was a 17-year-old bolter to Wimbledon glory and 19-year-old Svetlana Kuznetsova scored a stunning Flushing Meadows victory.

Last year does not touch the 1997 season, when a 16-year-old Martina Hingis won the Australian Open, Wimbledon and US Open, denied a grand slam clean sweep by 19-year-old Iva Majoli's shock French Open final win over the Swiss.

But women's tennis is still seeing a remarkable shift to relative youth.

The 2019 season saw a then 19-year-old Bianca Andreescu scoop a stunning US Open win, while Ash Barty took the French Open.

Andreescu has been sidelined with a knee injury since the 2019 WTA Finals, but she is back for Australia, where Queenslander Barty, now 24, is the home hero.

Brace for the prospect of Andreescu and Barty joining Kenin, Swiatek and Osaka in a group of five who can take the women's game boldly into the post-Williams era.

But the Williams era isn't over

This is true, and again Serena will make another attempt to land that elusive 24th grand slam, the one that would move her level with Margaret Court on the all-time list.

She remains, at the age of 39, a magnificent competitor and a beguiling player, as does sister Venus, who turns 41 in June.

Serena has lost her last four grand slam finals, however, and the most recent run to a title match came almost 18 months ago in New York, where Andreescu had her number.

As the new gang of five threaten to pull away from the old establishment, perhaps Williams is now in the next group, along with the likes of Simona Halep, Victoria Azarenka and Petra Kvitova: still perfectly capable of winning another slam or even multiple slams, but it feels important to strike now.

Serena has not won any of her last 10 slams, making it the longest span in her professional career without winning a major.

Barty party, or Sofia the second?

Osaka begins the Australian Open as favourite with bookmakers, but world number one Barty will have home support and could make that count. How she performs will be keenly watched, given she chose not to travel once the COVID-19 pandemic hit last year, sitting out 11 months.

Should Barty get on a roll, hopes will be high she can become the first Australian woman to take the title since Chris O'Neil in 1978. Last year, Barty fell in the semi-finals to Kenin, and she will be eager to land a second slam title.

Kenin, whose intense concentration and steely resolve helped her pull off last year's shock Melbourne win, and follow up with a run to the French Open final, can be a match for anyone. She will be aiming to become the first woman to win back-to-back Australian Open titles since Azarenka in 2012 and 2013.

Success on this level has come perhaps ahead of schedule for the American, and the same can be said for Swiatek, whose demolition of the field at Roland Garros in October made a mockery of her being ranked number 53 in the world.

The teenage Polish player became her country's first grand slam singles champion, and with that status comes the expectation she will follow it up. How that turns out for her will be one of the most intriguing of sub-plots in the new season.

Changing priorities

Halep said in a recent WTA interview that winning an Olympic medal was her "main goal" for 2021, although Osaka will also have the Tokyo Games firmly circled in her diary.

For the likes of those other players among the 16 slam winners in the Melbourne draw, there will be differing targets this year, too.

Angelique Kerber, Sloane Stephens, Jelena Ostapenko and particularly Garbine Muguruza may yet come good again on the big stage at some point this season.

For Venus Williams, Kuznetsova and Samantha Stosur, it may be a case of one final hurrah.

As the likes of Coco Gauff emerge as potential future big-stage winners, and fledgling ambassadors, the women's game looks in safe hands.